Scanning tunneling microscope

Abstract

A scanning tunneling microscope is disclosed which includes a frame assembly having upper frame members coupled to lower frame members by an external vibration isolation structure, a sample carousel configured to receive at least one sample to be scanned, and a probe carousel configured to receive at least one probe module including a probe tip. The sample and probe carousels are coupled to the upper frame members and sample and probe actuators are provided to rotate the carousels. A positioning mechanism is used to maintain a scanning distance between the probe tip and the sample carousel. A control unit controls the overall operation of the actuators to rotate the carousels and the operation of the positioning mechanism to maintain the scanning distance.

What is claimed is: 
     
       1. An apparatus comprising; a frame assembly including upper frame members coupled to lower frame members by an external vibration isolation structure;   a sample carousel constructed to receive at least one sample to be scanned and a probe carousel constructed to receive at least one probe module including a probe tip, said sample and probe carousels being coupled to said upper frame members;   a sample actuator and a probe actuator respectively coupled to said sample carousel and said probe carousel;   positioning means for maintaining a scanning distance between said probe tip and said sample carousel; and   control means for controlling the operation of said sample actuator and said probe actuator to rotate said sample and probe carousels and for controlling the operation of said positioning means to maintain said scanning distance.   
     
     
       2. An apparatus as claimed in claim 1, wherein: said external vibration isolation structure includes compression isolators.   
     
     
       3. An apparatus as claimed in claim 2, wherein: said compression isolators include a coil spring under compressive force and an elastomer located within said coil spring.   
     
     
       4. An apparatus as claimed in claim 1, wherein: said probe carousel is coupled to said upper frame member by a probe frame and said sample carousel is coupled to a sample frame that is coupled to said probe frame via a pivot connection.   
     
     
       5. An apparatus as claimed in claim 4, wherein: said positioning means includes an approach ramp movably coupled to said probe frame and an actuator means for moving said approach ramp, and   wherein said sample frame includes an approach roller that contacts said approach ramp.   
     
     
       6. An apparatus as claimed in claim 5, wherein: said actuator means includes a leadscrew assembly in contact with said approach ramp.   
     
     
       7. An apparatus as claimed in claim 6, wherein: said leadscrew assembly is coupled to said probe frame by a thermal expansion compensator.   
     
     
       8. An apparatus as claimed in claim 1, wherein: stationary contacts are located adjacent said probe carousel and said probe modules include switching contacts, and   said switching contacts make connection with said stationary contacts when said probe module is moved to a scanning position by said probe carousel.   
     
     
       9. An apparatus as claimed in claim 1, wherein: said sample and probe actuators include stepper motors respectively coupled to said sample and probe carousels by worm gear assemblies.   
     
     
       10. An apparatus comprising: sample carousel means for retaining at least one sample;   probe carousel means for retaining at least one probe unit including a probe tip coupled to a frame assembly;   actuator means coupled to said sample carousel means and said probe carousel means for independently rotating said sample carousel means and said probe carousel means to translationally dispose the probe tip relative to the sample in a predetermined scanning position; and   displacement means coupled to said frame assembly for controlling a relative vertical displacement between said probe tip and said sample.   
     
     
       11. An apparatus comprising: sample carousel means for retaining at least one sample;   probe carousel means for retaining at least one probe unit including a probe tip coupled to a frame assembly;   actuator means coupled to said sample carousel means and said probe carousel means for independently rotating said sample carousel means and said probe carousel means to a scanning position;   displacement means coupled to said frame assembly for controlling the relative vertical displacement between said probe tip and said sample; and   vibration isolation means for isolating said sample carousel means, said probe carousel means and said displacement means from external sources of vibration.   
     
     
       12. An apparatus as claimed in claim 11, further comprising: temperature compensation means located between said displacement means and said frame assembly for providing temperature compensation to prevent positioning errors due to thermal expansion and contraction.   
     
     
       13. A method of scanning tunneling microscopy, comprising the steps of: locating at least one sample on a rotatable sample carousel and at least one piezoelectric probe unit including a probe tip on a rotatable probe carousel;   isolating said sample carousel and said probe carousel from external vibrations;   controlling coarse lateral positioning of said sample with respect to said probe tip by controllably rotating said sample and probe carousels;   controlling coarse vertical positioning of said sample with respect to said probe tip by providing relative axial motion of said sample and probe carousels; and   controlling fine lateral and vertical positioning of said sample relative to said probe tip by applying control signals to said piezoelectric probe unit.   
     
     
       14. A method as claimed in claim 13, the further steps of: applying control scanning signals to said probe unit; and   analyzing sample signals generated by said probe unit, to produce a scanning tunneling microscopy image.   
     
     
       15. A method as claimed in claim 13, comprising the further step of; selecting a new sample by rotating said sample carousel.   
     
     
       16. A method as claimed in claim 13, comprising the further step of; selecting a new probe unit by rotating said probe carousel.   
     
     
       17. A scanning tunneling microscope comprising: a frame assembly including upper frame members coupled to lower frame members by compression isolators, each compression isolator including a coil spring under compressive force and an elastomer located within said coil;   a sample carousel constructed to receive at least one sample to be scanned and a probe carousel constructed to receive at least one probe module including a probe tip, wherein said probe carousel is coupled to said upper frame member by a probe frame and said sample carousel is coupled to a sample frame that is coupled to said probe frame via a pivot connection;   a sample actuator and a probe actuator respectively coupled to said sample carousel and said probe carousel;   a positioning mechanism including an approach ramp movably coupled to said probe frame and a positioning actuator coupled to said approach ramp, wherein said sample frame includes an approach roller that contacts and rides on said approach ramp; and   control means for controlling the operation of said sample actuator, said probe actuator and said positioning actuator to rotate said sample and probe carousels and for controlling the operation of said positioning means to maintain a scanning distance, between said probe tip and said sample.   
     
     
       18. An atomic force measurement device comprising: a frame assembly including upper frame members coupled to lower frame members by compression isolators, each compression isolator including a coil spring under compressive force and an elastomer located within said coil;   a sample carousel constructed to receive at least one sample to be tested and a probe carousel constructed to receive at least one probe module including a probe tip, wherein said probe carousel is coupled to said upper frame member by a probe frame and said sample carousel is coupled to a sample frame that is coupled to said probe frame via a pivot connection;   a sample actuator and a probe actuator respectively coupled to said sample carousel and said probe carousel;   a positioning mechanism including an approach ramp movably coupled to said probe frame and a positioning actuator coupled to said approach ramp, wherein said sample frame includes an approach roller that contacts and rides on said approach ramp; and   control means for controlling the operation of said sample actuator, said probe actuator and said positioning actuator to rotate said sample and probe carousels and for controlling the operation of said positioning means to maintain contact between said probe tip and a sample on said sample carousel.